2. Hydrocarbons
The three key categories of hydrocarbons are saturated, unsaturated, and
aromatic.
These categories have a large influence on both the reactivity and physical
properties of organic compounds.
Saturated hydrocarbons are relatively chemically inert.
Unsaturated hydrocarbons are subject to addition and oxidation reactions.
Aromatic hydrocarbons are more likely to undergo substitution reactions instead of
addition reactions.
Saturated Unsaturated Aromatic
3. Experimental Procedure
The three known compounds for the experiement are cyclohexane, cyclohexene,
and toluene.
Each student will receive one unknown prepared by the TA. Note your unknown’s
identifying code in your lab notebook.
For each procedure involving a solvent, a blank will be included that is just the
solvent for the test.
All test tubes should be clean and DRY. Residual water or acetone can interfere
with your tests.
For each test, your results must include both observations and interpretation for
each known and your unknown.
CH3
? Solvent
Cyclohexane Cyclohexene Toluene Unknown Blank
4. Solubility and Density
Put 2 mL of water in five (5) test tubes. Clearly mark your test tubes to identify which
type of hydrocarbon was added.
PART A: Add 2 to 3 drops of each liquid to it’s test tube and shake.
Record your observations of water solubility (don’t forget interpretation).
PART B: Reexamine your test tubes to determine if the non-soluble compounds
are more dense or less dense than water.
PART C: Skip this part. No open flames in Organic Chemistry Lab.
CH3
? water
Cyclohexane Cyclohexene Toluene Unknown Blank
5. Reaction with Bromine (Bromination)
Starting with freshly cleaned test tubes, add 1 mL of methylene chloride to five (5)
test tubes. Clearly mark your test tubes to identify which type of hydrocarbon was
added.
PART D: Add 3 to 4 drops of each liquid to it’s test tube.
Add several drops of bromine solution to each test tube and watch for a loss of color.
What does this color loss indicate?
Record your observations (don’t forget interpretation).
CH3
Methylene
? chloride
Cyclohexane Cyclohexene Toluene Unknown Blank
6. Reaction with KMnO4 (Oxidation)
Starting with freshly cleaned test tubes, add 1 mL of acetone to five (5) test
tubes. Clearly mark your test tubes to identify which type of hydrocarbon was
added.
PART E: Add 3 to 4 drops of each liquid to it’s test tube.
Add several drops of potassium permanganate solution to each test tube and
watch for a loss of color. What does this color loss indicate?
Record your observations (don’t forget interpretation).
CH3
? Acetone
Cyclohexane Cyclohexene Toluene Unknown Blank
7. Reaction with H2SO4
Starting with freshly cleaned test tubes, add 1 mL of concentrated sulfuric acid to
four (4) test tubes. Clearly mark your test tubes to identify which type of
hydrocarbon was added.
PART F: Add 3 to 4 drops of each liquid to it’s test tube, one drop at a time.
Carefully watch for signs of a reaction (sample dissolves, changes color,
becomes warm, or forms a precipitate). If no reaction occurs at room
temperature, warm the sample in a warm water bath.
Record your observations (don’t forget interpretation).
CH3
? None
Cyclohexane Cyclohexene Toluene Unknown Blank
8. Final Notes
There are three types of liquid waste bottles in the hood:
Aqueous (Parts A, B and D)
Organic (Part E)
Acid (Part F)
Both sulfuric acid and the bromine solution can cause burns.
Please handle carefully. (When shaking your test tubes, do you use
your thumb to cover the opening?)
Are you prepared for your MIDTERM?
